A tannin-derived zirconium-containing porous hybrid for efficient Meerwein-Ponndorf-Verley reduction under mild conditions

Both the use of renewable natural sources to prepare catalytic materials and the Meerwein-Ponndorf-Verley (MPV) reduction for carbonyl compounds are very attractive topics in catalysis. In this study, tannins were simply assembled with zirconium in water for the scalable preparation of a heterogeneous zirconium-tannin hybrid catalyst (Zr-tannin). Various characterizations demonstrated the formation of robust porous inorganic-organic frameworks and strong Lewis acid-base sites in Zr-tannin. The cooperative effect of these acid-base sites and the abundant porosity endowed Zr-tannin with a remarkable catalytic performance for the MPV reduction of a broad range of carbonyl compounds to alcohols with 2-propanol under mild conditions. Moreover, Zr-tannin exhibited good recyclability for at least five reaction cycles. This novel strategy using tannins as the raw materials to construct heterogeneous catalytic materials may have a huge potential for green chemical synthesis due to low cost, nontoxicity, and sustainability.